Last year, we had introduced to you a new campaign initiated by eCoexist called Punaravartan. This campaign aimed to collect and recycle clay sludge after the immersion of natural clay idols in water (visarjan). The eCoexist team had successfully carried out a pilot test of this activity and were able to make beautiful recycled clay idols. 

We are so delighted to let you know that for 2022, 15 organisations have joined hands with us to implement this project across the entire city of Pune! The campaign will also be replicated in Nasik by the Rotary club and in Gujarat by the Little Millenium group along with others. 

So much has happened in the last few months of planning this campaign and I am happy to share some of the highlights with you here ...

So... what is the Punaravartan campaign about ? Over the next few days we will be sharing with you more and more details of the campaign and letting you know how you can sign up to participate - but first lets discuss the concept behind it... 

In May 2020,  the Government of India, through the Central Pollution Control Board banned the use of Plaster of Paris and chemical paints , to make religious idols meant for immersion. This is a landmark decision that will ensure that our rivers, lakes and all water bodies stay free of any non biodegradable man made objects.

The immediate material to replace Plaster of Paris would be natural clay , shaadu maati - as it is known in Maharashtra. However, natural clay is a mineral resource - i.e. it is mined from the ground and therefore in limited supply. The mines where this clay comes from create an ecological disaster in the region of another scale. 

While the switch to natural clay is a good beginning, eventually if the entire festival turns to using natural clay it will not be a sustainable solution for the future. 

Is it possible to recycle the clay used for idols and create a closed loop?

Bentonite clay mines in Gujarat 

Source: Gujarat Mineral Development Corporation Ltd

Ball clay is an extremely rare mineral found in very few places around the world. Its name dates back to the early methods of mining when specialized hand tools were used to extract the clay in rough cube shapes of about 30 cm. As the corners were knocked through handling and storage these cubes became rounded and ball shaped. It also is sometimes referred to as plastic clay.

Ball clay consist of ultra fine clay particles. This helps to make them sticky (or 'plastic') and easily shaped when damp (the word 'clay' is derived from the Old English 'claeg', meaning sticky). Some also have fluid properties that are valuable in the casting of large ceramic pieces such as toilet bowls. Ball Clay is a variety of Kaolinite, like china-clay. It differs from china-clay in having high plasticity.

(Source: Gujarat Mineral Development Corporation Ltd)

To reduce the amount of clay that is mined from Nature it is possible to explore the recycling of clay sludge after the immersion ritual. When immersed in natural water bodies, this clay tends to form an impermeable sediment at the bottm of the lake or river and affect the ecosystems. When we do a home immersion the clay can be put into gardens and pots , but requires to be mixed with red earth for plants to grow in it.

For 2021, the eCoexist team decided to experiment with the recycling of damaged clay idols left over with us. 

We learnt of the process of 'slaking' which is normally used by sculptors and ceramic artists when handling clay. Slaking refers to the manner in which dry clay breaks down when immersed in or exposed to water. 

Typically the water attacks the surface and particles simply fall away. When slaking is complete a pile of fine material will be found settled on the bottom of the container of water, power mixing will then produce a slurry. Clays that slake well will break down in minutes if chunks are less than about 1 cm in size and all have exposure to the water. Very plastic clays may not slake since the wetting of the surface will cause swelling and act as a barrier to further water penetration.

Source : Digitalfire.com

Click on picture to watch a video of the recycling process

A very simple manual procedure was tested out with fair results. This involved

1. Immersion of clay idol

2. Drying of sludge

3. Powdering 

4. Sieving 

The powder so obtained was then sent to several ceramic artists and sculptors to test by making new idols . A small portion of fresh clay was added to some mixes and others were made entirely of the recycled powder. The resultant clay idols were as good as new. The procedure involved minimal quantitative loss of clay. 

Is this a solution that could be scaled up to make an impact on the mining of ball clay ? What would it entail to create a circular economy around this one material and product? 

The first step in closing the loop is to ensure that the sludge from the old clay is recollected after visarjan - this will involve some cooperation on part of the devotees. It will also require a collection system to be established for the city.

Recycling also involves costs of collection, transportation and storage and a cost benefit analysis needs to be done to check if the short term costs of recycling balance out the fresh mining of clay. In the long term of course, recycling of minerals is surely a more sustainable option. 

In terms of quality, it appears that slaking renders the clay finer and therefore improves on the quality of the recycled product, however we need to check for how many cycles this holds true until new clay needs to be added to ensure the same quality. 

The use of paints on the clay idols will also affect the quality of recycled powders, as the particles of paints will be mixed into the sludge and will be hard to seperate from the recycled powder. 

Ideally no man made substance should be allowed to be put into natural water bodies which are living habitats and eco systems.

The revised guidelines of CPCB also advise about treatment of water after immersion as well the need for desludging ... 

Lime or alum or any other equivalent coagulant should be added in designated temporary lined pond/tank as pre-treatment option for ensuring settling of solids. After completion of immersion, only supernatant water may be allowed to flow into river/pond/lake, as the case may be, after checking for colour and turbidity as per BIS specification for Drinking Water IS 10500:2012. 

Post immersion, with remains of idols and activities such as desludging of the designated area should be undertaken and ensured its disposal as per Solid Waste Management Rules 2016 as amended thereafter, within 24 hours by the concerned ULBs, as per these guidelines.

What is to be done with this sludge? If appropriately harvested treated and recycled natural clay sludge can conserve our clay resources while ensuring our water bodies stay clean.

1. How does one collect clay at home ? 

2. Where can we give it in Pune ?

3. What will happen to this clay ? 

4. Who is involved in this campaign?

5. How can societies or corporate groups participate ?

6. How can we tell the difference between Plaster of Paris and clay idols?